Low-Temperature and Solution-Processable Zinc Oxide Transistors for Transparent Electronics

Abstract

Zinc oxide (ZnO) thin-film transistors (TFTs) have many promising applications in the areas of logic circuits, displays, ultraviolet detectors, and biosensors due to their high performances, facile fabrication processing, and low cost. The solution method is an important technique for low-cost and large fabrication of oxide semiconductor TFTs. However, a key challenge of solution-processable ZnO TFTs is the relatively high processing temperature (≥500 °C) for achieving high carrier mobility. Here, facile, low-cost, and solution-processable ZnO TFTs were fabricated under the annealing temperature of ≤300 °C. Dense and polycrystalline ZnO films were deposited by the spin-coating method. The ZnO TFTs showed the maximum electron mobility of 11 cm 2 /V s and a high on/off ratio of >10 7 when the ZnO thin films were annealed at 300 °C. The mobility was extremely high among solution-processable undoped ZnO TFTs reported previously, even better than some high-cost indium-doped ZnO TFTs fabricated at low temperature. Furthermore, it is found that the mechanism of oxygen vacancies dominates the electron transport in ZnO thin film and interface behaviors of ZnO thin film and SiO 2 gate insulator, and then dominates the performances of devices.

Inkjet-printed ZnO thin film semiconductor for additive manufacturing of electronic devices

“…The excess oxygen generally decreases when a higher temperature was used, such as from 40.1 % to 28.8 % at 350 °C, except at 300 °C where the percentage of excess oxygen is 50.3 %. This result is complied with previous study [227]. It is suggested that the excess oxygen mainly converts to oxygen vacancies at a temperature lower than 300 °C.…”

“…The sub-peak at 531.0 eV is associated with oxygen vacancies and is denoted as O2. The sub-peak located at the highest binding energy is associated with surface-adsorbed oxygen-containing species and is denoted as O3 [111,227].…”

“…At the temperature higher than 300 °C, oxygen vacancies convert to lattice due to the oxygen vacancies are filled by free oxygen. It could be because high temperature could increase the atom gaps of ZnO crystal, which allows more oxygen atoms to enter the gaps [227].…”

Enhancing the Diode Characteristics of Pulsed Laser–Deposited n‐MgxZn1−xO/p‐Si Heterojunction: Role of Oxygen Ambient Pressure

“…The medium binding energy component O V , centered at 531.2 eV, is associated with O 2− ions in the oxygen‐deficient regions within the Mg x Zn 1 − x O matrix. [ 34,35 ] Therefore, variation in intensity/area of the O V component indicates the change in concentration of oxygen vacancy in the film matrix. It can be clearly seen from Figure 6a,b that the relative intensity/area of the O V peak decreases as the oxygen ambient pressure increases from 1.0 × 10 −2 to 1.0 × 10 −1 mbar, indicating a decrease in the concentration of oxygen vacancies at higher oxygen growth pressures leading to low free carrier concentration.…”

On-Substrate Joule Effect Heating by Printed Micro-Heater for the Preparation of ZnO Semiconductor Thin Film

“…These advantages of inkjet printing have been widely employed for the fabrication of semiconductor devices [3,4]. Thanks to its outstanding features and abundance, zinc oxide (ZnO) has attracted considerable attention and effort in the additive fabrication of electronics devices such as solar cells [5,6], photodetectors [3,7], and transistors [8,9]. Additive manufacturing of inorganic material from a precursor compound usually requires a heat treatment step in order to convert precursors to the required material [10,11].…”